Thermally insulated iceboxes or ice chests for preserving food find use for picnics and outings in trailers and campers, and aboard boats and airplanes. It is sometimes desirable to replace these iceboxes with electrical refrigerators but, due to space or cost limitations, this is not always feasible. Generally, aboard a boat the iceboxes are built-in and an integral part of the galley, and there is insufficient space to add a refrigerator. Even if the icebox could be removed, a refrigerator generally would not fit in the space formerly occupied by the icebox because, for example, boats are not rectangular and do not have square corners. Thus, the icebox may have a curved back wall at the lower corners, whereas refrigerators are generally rectangular and have square corners. For this reason, refrigerators have sometimes been strapped into bunks, taking up needed bed space.
One alternative is to convert the icebox to a compressor type refrigerator. However, these are expensive and complex. A better alternative is to convert the icebox to a refrigerator by installing the cooling unit from a thermoelectric refrigerator. However, these are not always adaptable to easy and convenient installation into any given insulated enclosure. U.S. Pat. No. 3,412,566 shows a refrigerator cooled by a thermoelectric unit, but the thermoelectric unit is built as an integral part of the refrigerator. The inner wall of the refrigerator itself serves as the cold plate, and the components of the thermoelectric unit are assembled into the wall of the refrigerator at the time the refrigerator is built. After the elements are assembled into the wall, the space within the wall is filled with insulation.
Similarly, U.S. Pat. No. 3,821,881 shows a refrigerator having a thermoelectric unit built into the door. The door is of a special shape and configuration, and the components of the thermoelectric unit are assembled into the door at the time it is built, and tightening the assembly effectively clamps the unit into the door. Clearly, such cooling units do not lend themselves to easy installation in an existing insulated enclosure because they are not constructed as fully-assembled, compact, self-contained units which will mount easily in a proper size hole made in any insulated enclosure.
In my above-mentioned U.S. Pat. No. 4,007,600, I described a thermoelectric refrigeration unit which is simple, compact, and self-contained, and in which the entire unit is easily fastened into a hole made in an existing insulated enclosure. The refrigeration unit is relatively inexpensive to install and economical to operate and will operate with any available source AC or DC. Furthermore, the refrigeration unit operates silently, is not sensitive to motion, is light in weight, and can be mounted on the top, bottom, or any side of an existing enclosure because it does not require that any particular side be maintained in an upright position. While a decided improvement over the prior art, it was found that still further improvements could be made. For example, it is constructed of a multiplicity of elements and connecting hardware which adds to its weight and cost. Assembly requires a moderate degree of skill in the factory with some likelihood of rejects. In addition, the existence of several parts decreases its thermal efficiency because the heat must be conducted through a multiplicity of thermal junctions with sharp corners, both of which offer resistance to thermal conductivity.